The ACC–Big Ten Challenge (or Big Ten–ACC Challenge as it is called in alternating years) is an in-season NCAA men's college basketball series established in 1999 that matches up teams from the Atlantic Coast Conference (ACC) and the Big Ten Conference. ESPN was a key part of the creation of the challenge, and holds the broadcast rights to all the games.

The ACC leads the series 10-4-2; the ACC won the first 10 consecutive challenges, while the Big Ten won the next three. The following two challenges resulted in ties. The most recent challenge was won by the Big Ten 8-6. In the 16 years of the event, seven of the challenges have been decided by a single game.

The Big Ten–ACC Challenge occurs early in the season, typically around late November/early December. Each game is hosted by one of the participating schools, with teams typically alternating home and away status in each successive year.

Nine games were played for each of the first 6 challenges, leaving two teams from the 11-team Big Ten Conference without an opponent. With the expansion of the ACC to 12 teams with the addition of Boston College, Miami and Virginia Tech, the field was expanded to 11 games in 2006, meaning that one ACC team would not play. With Nebraska joining the Big Ten in 2011, the challenge expanded to 12 games and every member from both conferences participated. In 2013, Syracuse, Pittsburgh, and Notre Dame joined the ACC, leaving three ACC teams excluded from the competition. In 2014, Maryland withdrew from the ACC and joined the Big Ten along with Rutgers, giving that conference 14 teams, and Louisville joined the ACC, replacing Maryland and maintaining the conference's 15-team membership. The conference realignments have led to the challenge being expanded to 14 games.

Imbalances in the number of teams in the conferences are resolved by dropping the larger conference's lowest finisher(s) in the prior season from the challenge pool, although in 2014 the ACC elected to exclude Boston College instead of last-place Virginia Tech to avoid excluding Virginia Tech in consecutive years.[citation needed]

When the challenge was expanded to 12 games, the change resulted in the possibility that the challenge could end in a tie. In the event of a tie, the previous year's winner retains the Commissioner's Cup. This scenario occurred in 2012 and 2013, with the Big Ten retaining the Cup based on its 8-4 win in 2011.[1]

Game Times in EST. Home team is italicized. Winners are in bold.
Rutgers and Louisville made their inaugural appearances in the event.
Boston College did not play due to the ACC having one more team than the Big Ten.
First ACC–Big Ten Challenge in which Maryland represents the Big Ten, as they left the ACC in 2014.
ACC–Big Ten Challenge expands to 14 games with the addition of Maryland and Rutgers to the Big Ten.

Game Times in EST.
Notre Dame, Pittsburgh, and Syracuse made their inaugural appearances in the event.
Clemson, Virginia Tech, and Wake Forest did not play due to all three teams finishing at the bottom in the ACC during the 2012–2013 season.
Last ACC–Big Ten Challenge in which Maryland represented the ACC, as they joined the Big Ten in 2014.

Considering that Maryland was the last ACC team in, and Wake Forest the first out, based on the previous ACC standings, some Wake Forest supporters argued that since Maryland had already established that it would leave the ACC for the Big Ten, the Terrapins should have been left out of this season's Challenge due to the conflict of interest and Wake should have played instead. [2]

Game Times in EST. Rankings from ESPN Coaches Poll (Nov. 30). #23 Georgia Tech did not play due to its last place finish in the ACC during the 2008–2009 season.
The North Carolina/Michigan St. match-up was a rematch of the 2008–09 NCAA Championship game.